WO2023093756A1

WO2023093756A1 - Light-emitting apparatus and manufacturing method therefor, and electronic device comprising light-emitting apparatus

Info

Publication number: WO2023093756A1
Application number: PCT/CN2022/133688
Authority: WO
Inventors: 甄常刮; 高远; 彭军军; 杜勇; 顾辛艳
Original assignee: 纳晶科技股份有限公司
Priority date: 2021-11-25
Filing date: 2022-11-23
Publication date: 2023-06-01
Also published as: CN116193923A

Abstract

The present disclosure relates to a light-emitting apparatus and a manufacturing method therefor, and an electronic device comprising a light-emitting apparatus. The light-emitting apparatus comprises: a first substrate; a plurality of first electrodes, which are located on the first substrate; and a stack of functional layers, which are located on the plurality of first electrodes, wherein the stack at least comprises a light-emitting layer, the light-emitting layer comprises a plurality of units which are independent of each other, and the plurality of units are arranged corresponding to corresponding first electrodes, wherein an isolation structure that extends from the first substrate or the first electrodes to the height of the plurality of units or to above same so as to separate the plurality of units is not arranged between the plurality of units.

Description

Light-emitting device, manufacturing method thereof, and electronic equipment including light-emitting device

technical field

The present disclosure relates to a light emitting device, a method of manufacturing the same, and an electronic device including the light emitting device.

Background technique

Light emitting devices such as light emitting diodes are widely used in lighting and display fields. In a display device, a pixel definition layer (PDL) for defining pixels is generally provided. Usually, the pixel defining layer is in the form of an isolation structure (bank) for defining pixels (or sub-pixels), thereby separating the pixels (or sub-pixels). A pixel-defining layer (bank) is generally fabricated on a substrate (also referred to as a TFT substrate) with active devices such as thin film transistors (TFTs).

However, in the prior art, using the same electrode material, functional laminate material and thickness design of each film layer, the performance of the light-emitting device prepared by the printing method is much lower than that of the light-emitting device prepared by the planar spin coating method.

The present disclosure provides a novel light emitting device having improved performance, uniformity of light emission, and the like.

Contents of the invention

According to one aspect of the present disclosure, there is provided a light emitting device, including: a first substrate; a plurality of first electrodes located on the first substrate; and a stack of functional layers located on the plurality of first electrodes, The laminate includes at least a light-emitting layer, and the light-emitting layer includes a plurality of units independent of each other, and the plurality of units are arranged corresponding to the corresponding first electrodes, wherein no slaves are arranged between the plurality of units. The first substrate or the first electrode extends to or above the height of the plurality of units to separate the isolation structures of the plurality of units.

In one embodiment, the isolation structure is a pixel defining layer for defining pixels.

In one embodiment, the orthographic projection of each unit of the plurality of units on the first substrate covers the orthographic projection of the corresponding first electrode on the first substrate, wherein the plurality of units and the A plurality of first electrodes are arranged in one-to-one correspondence.

In one embodiment, the plurality of units are configured separately from each other. In one embodiment, the stack further includes an upper functional layer on the light emitting layer, at least a part of the upper functional layer is located between units of the plurality of units.

In one embodiment, between said units, said at least a portion of said upper functional layer is in contact with a portion of a lower functional layer below said light-emitting layer that is not shielded by said light-emitting layer.

In one embodiment, the light emitting device further comprises: a second electrode located on the stack, wherein each unit of the plurality of units of the light emitting layer, the corresponding first electrode and the Corresponding portions of the second electrodes are included in corresponding pixels.

In one embodiment, the laminate further includes: a lower functional layer under the light-emitting layer, wherein the portion of the lower functional layer that overlaps with the unit of the light-emitting layer is not the same as that of the lower functional layer. The surface properties of the portion overlapping with the unit of the light-emitting layer are consistent.

In one embodiment, the plurality of units of the light-emitting layer are formed by drying printed ink droplets containing quantum dot materials, and the plurality of units are configured, in a top view: for For any unit, the lateral size of the unit is greater than or equal to the sum of the lateral size of the first electrode corresponding to the unit and twice the printing accuracy of the nozzle used for printing; between two adjacent units, the The distance between the centers of the two first electrodes corresponding to the two adjacent units is greater than or equal to the sum of half of the respective lateral dimensions of the two adjacent units and twice the printing accuracy of the nozzles used for printing.

In one embodiment, the stack further includes one or more functional layers below or above the light-emitting layer, wherein the one or more functional layers include at least one of the following: a hole injection layer , hole transport layer, electron injection layer, electron transport layer, electron blocking layer, buffer layer.

In one embodiment, the light-emitting device is a bottom-emission light-emitting device, a top-emission light-emitting device or a double-side-emission light-emitting device.

In one embodiment, each of the plurality of units of the light-emitting layer and the corresponding first electrode are included in a corresponding pixel, a transistor is formed in the first substrate, and the light-emitting device further It includes: an opposite second substrate; and a spacer arranged between the first substrate and the second substrate, and the spacer is arranged offset from the pixel.

According to another aspect of the present disclosure, there is also provided a method for manufacturing a light-emitting device, including: providing a first substrate having a plurality of first electrodes thereon; and forming a stack of functional layers on the first substrate, the The laminate includes at least a light-emitting layer, and the light-emitting layer includes a plurality of units independent of each other, and the plurality of units are arranged corresponding to the corresponding first electrodes, wherein no slave from the first electrode is arranged between the plurality of units. The substrate or the first electrode extends to or above the height of the plurality of cells to separate the isolation structures of the plurality of cells.

In one embodiment, forming a stack of functional layers on the first substrate includes: forming an electrode corresponding to the plurality of units of the light-emitting layer corresponding to the plurality of first electrodes by using an ink drop printing method. a liquid printing unit, the ink drop contains a quantum dot material; the liquid printing unit is dried to form the plurality of units of the light-emitting layer; wherein each unit of the plurality of units is in the first The orthographic projection on the substrate overlays the orthographic projection of the corresponding first electrode on the first substrate.

In one embodiment, forming the stack of functional layers on the first substrate further includes one or more of the following: forming a lower functional layer, the lower functional layer covering at least the plurality of first electrodes, Wherein the plurality of units of the light-emitting layer are located on the lower functional layer, and the portion of the lower functional layer that overlaps with the units of the light-emitting layer is the same as that of the lower functional layer that is not overlapped with the light-emitting layer. The properties of the overlapping parts of the units are consistent; and an upper functional layer is formed, and the upper functional layer covers the plurality of units of the light emitting layer.

In one embodiment, the orthographic projection of each unit of the plurality of units on the first substrate covers the orthographic projection of the corresponding first electrode on the first substrate.

In one embodiment, the plurality of units is configured such that the plurality of units are separated from each other. In one embodiment, at least a portion of said upper functional layer is located between units of said plurality of units.

In one embodiment, the plurality of units are configured such that, in a top view: for any unit, the lateral dimension of the unit is greater than or equal to the transverse dimension of the first electrode corresponding to the unit and the nozzle used for printing The sum of twice the printing accuracy; between two adjacent units, the distance between the centers of the two first electrodes corresponding to the two adjacent units is greater than or equal to the respective distance between the two adjacent units The sum of half the horizontal dimension and twice the printing accuracy of the nozzle used for printing.

In one embodiment, the upper functional layer or the lower functional layer comprises at least one of the following: a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, an electron blocking layer, and a buffer layer.

In one embodiment, the method further includes: forming a second electrode on the stack of functional layers, wherein each unit of the plurality of units of the light emitting layer, the corresponding first electrode and the Corresponding portions of the second electrodes are included in corresponding pixels.

In one embodiment, the method further includes: providing a spacer, wherein the spacer is disposed on a side of the second electrode away from the first electrode, and is disposed offset from the pixel.

According to another aspect of the present disclosure, there is also provided an electronic device, which includes the light emitting device according to any embodiment or implementation manner of the present disclosure.

Other features of the present disclosure and advantages thereof will become apparent through the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings.

Description of drawings

The accompanying drawings, which constitute a part of this specification, illustrate the embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.

The present disclosure can be more clearly understood from the following detailed description with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic diagram of the preparation of a light-emitting device by an inkjet printing method in the prior art;

Fig. 2 shows a schematic diagram of a light emitting device according to an embodiment of the present disclosure;

Fig. 3 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure;

4A-4C are schematic diagrams illustrating the relationship between a unit of a printed light-emitting layer and a lower electrode according to an embodiment of the present disclosure;

5A and 5B are schematic diagrams illustrating the relationship between units of a printed light-emitting layer and lower electrodes according to another embodiment of the present disclosure;

6A-6E show schematic diagrams of a method for fabricating a light-emitting device according to an embodiment of the present disclosure;

Fig. 7 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure;

Fig. 8 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure;

Fig. 9 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure; and

FIG. 10A shows a photomicrograph of a printed quantum dot (QD) layer in a light-emitting device prepared according to an example of the present disclosure, and FIG. 10B shows a stalk scan result corresponding to the region shown in FIG. 10A .

Note that in the implementations described below, the same reference numerals are sometimes used in common between different drawings to denote the same parts or parts having the same functions, and repeated description thereof will be omitted. In this specification, similar reference numerals and letters are used to refer to similar items, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

In order to facilitate understanding, the position, size, range, etc. of each structure shown in the drawings and the like may not represent the actual position, size, range, and the like. Therefore, the disclosed invention is not limited to the positions, dimensions, ranges, etc. disclosed in the drawings and the like.

Specific implementation

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise. In addition, techniques, methods, and devices known to persons of ordinary skill in the related art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the authorized specification.

It should be understood that the following description of at least one exemplary embodiment is illustrative only, and not intended to limit the present disclosure and its application or use. It should also be understood that any implementation described by way of example herein is not necessarily meant to be preferred or advantageous over other implementations. The present disclosure is not to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or detailed implementation.

In addition, certain terms may also be used in the following description for reference purposes only, and thus are not intended to be limiting. For example, the words "first," "second," and other such numerical terms referring to structures or elements do not imply a sequence or order unless clearly indicated by the context.

It should also be understood that when the word "comprises/comprises" is used herein, it indicates the presence of indicated features, integers, steps, operations, units and/or components, but does not exclude the presence or addition of one or more other features, whole, steps, operations, units and/or components and/or combinations thereof.

In prior art light emitting devices such as display devices, the height of the isolation structure (bank) used as the pixel defining layer is generally several micrometers (μm). When the functional layer such as the luminescent layer is prepared by ink printing, the ink droplets are affected by the capillary effect at the isolation structure, and will form accumulations at the edge of the isolation structure after drying, resulting in uneven film layers. As shown in Figure 1.

FIG. 1 shows a schematic diagram of preparing a light-emitting device by an inkjet printing method in the prior art. As shown in FIG. 1 , a pixel defining layer for defining pixel regions is formed on the substrate 1101 , which includes a plurality of isolation structures 1103 . The ink droplet 1107 containing the material for forming the functional layer is spray-printed on the substrate 1101 through the nozzle 1105, so as to print the functional layer, such as a light emitting layer, etc. in the pixel area defined by the pixel defining layer. However, as shown in Figure 1, the printed ink droplets are affected by the capillary effect at the isolation structure, and the droplets will wet along the surface of the isolation structure, causing the film thickness at the edge to be larger than that at the center, so that after drying Material builds up at the edges of the isolation structure, resulting in an uneven film layer.

The uniformity of the film layer of the light-emitting diode is affected by the isolation structure (capillary effect), and it is difficult to achieve uniformity and flatness. Moreover, light-emitting diodes can include multi-layer films (such as hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, etc.), so it is more difficult to make multi-layer films by printing. until the film layer is even and smooth.

On the other hand, the upper electrode has poor lap stability at the isolation structure. The upper electrode usually covers the functional layer and the top of the isolation structure in its entirety, and is usually made thinner, and the total thickness of the electrode film layer is usually only a few hundred nanometers (nm). The height of the isolation structure is usually several micrometers. Therefore, the height difference between the isolation structure and the total thickness of the film layer is very large, which may easily cause the upper electrode to break.

Therefore, in the prior art, using the same electrode material, functional lamination material and thickness design of each film layer, the performance of the light-emitting device prepared by the printing method is much lower than that of the light-emitting device prepared by the planar spin coating method.

The present disclosure aims at at least one or more of the above-mentioned problems, and provides a novel light-emitting device with improved performance, uniformity of light emission, and the like.

Embodiments according to the present disclosure will be specifically described below with reference to the accompanying drawings.

Fig. 2 shows a schematic diagram of a light emitting device according to an embodiment of the present disclosure. As shown in FIG. 2 , the light emitting device 200 includes a first substrate 101 . A plurality of first electrodes 103 are formed on the first substrate 101 . The light emitting device 200 further includes a stack of functional layers (not denoted by reference numerals) located on the plurality of first electrodes. The stack includes at least a light-emitting layer, and the light-emitting layer includes a plurality of units 107 that are independent of each other. In the embodiment shown in Figure 2, the plurality of units 107 are shown separated from each other. The plurality of units 107 are arranged corresponding to the corresponding first electrodes, for example, in some implementations, the units 107 may be arranged in one-to-one correspondence with the first electrodes 103 .

In the light emitting device according to the present embodiment, no isolation structure extending from the first substrate or the first electrode to the height of the unit 107 or above to separate the plurality of units is provided between the plurality of units 107 . In other words, in the light emitting device of the embodiment of the present disclosure, there is no pixel defining layer in the prior art.

In this embodiment, the multiple units 107 are configured such that the orthographic projection of each unit 107 on the first substrate 101 covers the corresponding orthographic projection of the first electrode 103 on the first substrate. In this way, luminous efficiency can be improved. On the other hand, the influence of adjacent pixels (or sub-pixels) on the current pixel (or sub-pixels) can also be reduced. More details will be described later in conjunction with FIGS. 4A-4C and 5A and 5B. Herein, the light emitting layer may also be denoted by reference numeral 107 when necessary.

In Fig. 2, a lower functional layer 105 below the light-emitting layer (which includes the unit 107) and an upper functional layer 109 above the light-emitting layer are also shown. Those skilled in the art will readily understand that one or more of the lower functional layer 105 or the upper functional layer 109 is optional. In addition, although the lower functional layer 105 and the upper functional layer 109 are shown as a single layer in FIG. 2, they may be multi-layered. In addition, although in the embodiment shown in FIG. 2, one or more functional layers are shown as a monolithic form, that is, the functional layer can be used for multiple pixels or sub-pixels, but in other embodiments In , the functional layer can also include multiple units, and a single unit can be used for one or more pixels or sub-pixels.

Here, the functional layer has a general meaning in the art. As an exemplary description, the functional layer may mean: a layer for a light emitting unit disposed between two electrodes of the light emitting unit. Functional layers may include at least one of a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, an electron blocking layer, a buffer layer, and/or any layer that performs other desired functions, and the like. In some implementations, electrodes or functional layers can be shared by two or more pixels.

In the implementation shown in FIG. 2 , the plurality of units 107 are shown separated from each other, with at least a portion of the upper functional layer 109 located between units of the plurality of units 107 . In this embodiment, the multiple units 107 are arranged on the same layer. In other words, the plurality of units 107 are arranged in the same layer, and the thicknesses are substantially the same within the range of process precision.

In some embodiments, between light-emitting layer unit 107 and unit 107, at least a portion of upper functional layer 109 is in contact with a portion of lower functional layer 105 below the light-emitting layer that is not shielded by said light-emitting layer.

In some embodiments, the units of the emissive layer are formed by drying printed ink droplets containing quantum dot material. In this way, a quantum dot display device can be formed. In some implementations, quantum dots can be configured to be uniformly dispersed in ink droplets. In some embodiments, a portion of the lower functional layer 105 (or one or more layers thereof) below the light-emitting layer 107 may be treated so that its surface properties are different from other portions, thereby affecting the spreading of ink droplets. Influence. For example, part of the surface of the lower functional layer (or one or more layers thereof) can be treated with ultraviolet light, thereby changing its hydrophilicity, hydrophobicity or other properties. However, since the functional layers are usually layers that have requirements for optoelectronic properties or other properties, and their components are complex, such treatment may cause adverse effects on optoelectronic properties, chemical properties, or surface flatness, thereby affecting device performance. . In addition, in the process of patterning through surface affinity treatment, the materials of each functional layer are required to have the same surface affinity, so the material selection of the functional layer is more stringent, and at the same time, the photoelectric performance of the light-emitting device needs to be considered. Therefore, in a more preferred embodiment, such a treatment is not performed, but the portion of the lower functional layer that overlaps with the units of the light-emitting layer overlaps with the units of the lower functional layer that do not overlap with the units of the light-emitting layer The surface properties of the overlapping parts are consistent. In this way, the process complexity is reduced, the preparation efficiency is improved, the cost is reduced, and the impact on device performance is minimized.

Fig. 3 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure. Compared with the light emitting device 200 shown in FIG. 2 , the light emitting device 300 further includes a second electrode 301 located on the stack of functional layers. According to requirements, in some implementations, the second electrode 301 may be a whole electrode (or a blanket electrode), which may cover the functional layers of multiple pixels. However, the present disclosure is not limited thereto. In some implementations, the second electrode 301 can be configured to allow light emitted by the light emitting layer to transmit therefrom. Exemplarily, the thickness of the second electrode 301 may be hundreds of nanometers, such as 100nm-200nm.

Each of the plurality of units 107 of the light emitting layer, a corresponding portion of the corresponding first electrode 103 and the second electrode 301 may be included in a corresponding pixel. The corresponding first electrode 103 , the corresponding part in the stack of functional layers, and the corresponding part of the second electrode 301 together constitute a light emitting unit (or called a light emitting device). Generally, a pixel may include one or more light emitting units. A pixel may also include a plurality of sub-pixels, each sub-pixel having a light emitting unit. For example, a pixel may include red, green and blue (RGB) three light emitting units (which may also be referred to as sub-pixels).

In some embodiments, the light emitting device 300 may further include a cover layer 303 disposed on the second electrode 301 . The covering layer is configured to allow the light transmitted from the second electrode to pass through, and the covering layer can improve the light extraction efficiency of the device.

In some embodiments, the cover layer may be composed of a high refractive index (n) material, typically n is greater than 1.65, preferably greater than 1.8. The thickness of the covering layer can range from tens of nanometers to several thousand nanometers. In some implementations, the covering layer can be made of organic small molecule materials, such as NPB, Alq, CBP, etc., by a thermal evaporation process; the thickness of the covering layer can be, for example, 20nm-400nm. In some implementations, the cover layer can be made of inorganic materials, such as Al ₂ O ₃ , _Six N _y , _Six N _y O _z , etc.; the thickness can be, for example, 20nm-400nm. In some implementations, the covering layer can be made of organic-inorganic hybrid materials by wet film-forming processes, such as slit coating, inkjet printing, ultrasonic spraying, screen printing, etc.; the thickness can be, for example, 300nm-3000nm. The organic material may be polymer resin, such as acrylic resin, epoxy resin, etc., or may be selected from polymethyl methacrylate, polycycloolefin, etc. The inorganic material may be selected from metal compound particles such as alumina, titania, zirconia and the like. Preferably, the particle size of the inorganic particles generally does not exceed 1000 nm.

In different implementations, the light-emitting device according to the present disclosure may be a bottom-emission light-emitting device that emits light through the first electrode and the first substrate, a top-emission light-emitting device that emits light through the second electrode, or a double-sided light-emitting device that emits light through both. Luminous type light emitting device.

4A-4C illustrate schematic top views of the relationship of cells of a printed emissive layer to a lower electrode (also referred to as a bottom electrode) according to one embodiment of the present disclosure. In this example, the lower electrode 103 is shown as circular. The cells 107 of the luminescent layer are also shown as circular. In plan view, the unit 107 of the light emitting layer covers the lower electrode (ie, the first electrode) 103 . That is to say, the orthographic projection of the unit 107 of the light emitting layer on the first substrate 101 covers the orthographic projection of the corresponding first electrode 103 on the first substrate. Here, those skilled in the art can easily understand that the shape of an actual ink drop after drying may be close to a circle, but it is difficult to achieve a perfect circle. Here, a circle is taken as an example for theoretical calculation. However, in practical applications, those skilled in the art can easily perform calculations according to actual needs according to the principles taught in this application.

In some embodiments, the light-emitting layer is fabricated by ink droplet printing. In this case, the cells formed by ink droplet printing preferably cover the lower electrodes. As shown in FIG. 4A , assuming that the radius of the circular unit 107 (which can be regarded as half of the lateral dimension (diameter)) formed after ink droplet drying is R, the radius of the lower electrode 103 is r, and the accuracy of printing (for example, The deviation of ink drop point) is a. Assume that in an ideal situation, the center of the circular unit 107 formed after the printed ink droplet dries coincides with (aligns with) the circular lower electrode 103 . Here, it should be noted that the alignment of the nozzle of the printing device with the lower electrode can be realized through the built-in function of the device (for example, automatic alignment of the CCD camera), and the accuracy of the landing point is determined by the printing device.

Then considering the accuracy of printing (for example, the deviation of the ink drop point) a, the radius R of the circular unit 107 formed after the ink drop is dried should be greater than or equal to the radius r of the lower electrode 103 and the printing accuracy (for example, the printing accuracy). The sum of point errors) a, that is, R≥r+a. Therefore, it can be ensured that the units 107 of the light-emitting layer formed by printing can completely cover the lower electrode 103 under the condition of the printing accuracy a.

In the absence of significant leakage, generally, only the portion of the printed emissive layer that overlaps the lower electrode emits light.

FIG. 4B shows two adjacent units 107 of the light emitting layer and corresponding adjacent two lower electrodes 103 . As shown in FIG. 4B , the radii of the two units 107 are R1 and R2 respectively, the printing precisions are a1 and a2 respectively, and the radii of the two lower electrodes 103 are r1 and r2 respectively. They respectively satisfy the above conditions, that is, R1≥r1+a1, R2≥r2+a2.

The center-to-center distance d between two adjacent lower electrodes 103 is configured to be greater than or equal to the sum of the radii R1 , R2 of the two units 107 and the printing accuracy a1 , a2 . That is, d≥R1+R2+a1+a2. In the case of R1=R2=R, r1=r2=r, and a1=a2=a, the pitch d≧2R+2a≧2r+4a.

It should be understood that the setting of the size of the film layer and the size and spacing of the lower electrodes after the ink droplets are dried can be designed according to different display resolutions, different pixel designs (for example, different geometric shapes and sizes), and whether partial overlapping designs are allowed. , equipment accuracy, etc. to consider.

As an illustrative example, the following situation may be considered. Set the initial conditions: 150ppi resolution, form 4 equal-sized circular lower electrodes (1 red, 1 green, 2 blue), and the accuracy of the printing equipment is 10 microns, as shown in Figure 4C. The side length of a corresponding square pixel may be 169 microns (25400 microns/150), and the distance between the lower electrodes is half of the side length 169/2=84.5 microns. Since 2R+2a≤d, that is, R≤(d-2a)/2=(84.5-2*10)/2=32.25 microns, that is, the radius of the unit formed after the ink droplet is dried is at most 32.25 microns. At the same time, r≤R-a=22.25 microns, that is, the maximum radius of the lower electrode is 22.25 microns, corresponding to a maximum opening ratio of 21.7%.

Therefore, the substrate resolution and pixel design determine the lower electrode spacing, the lower electrode spacing and printing equipment accuracy determine the upper limit of the diameter of the unit formed by ink droplets, and the diameter of the unit formed by ink droplets (experimental value) determines the upper limit of the radius of the lower electrode.

Here, the circular lower electrode is just an example, and its opening ratio is relatively low as shown above, but it matches the natural drying shape of the printed ink droplet, and it is convenient to discuss the distance between the lower electrodes. The same principle can be applied in actual products to configure cells and electrodes with desired geometries. For example, rectangular electrodes are used in an embodiment to be described later.

In addition, the radius R of the unit formed by ink drop printing may be affected by the following factors: ink formulation, size and shape of the lower electrode. The formulation of the ink can be adjusted to change its spreading radius. Generally, the greater the surface tension of the ink, the smaller the spread, and the smaller the surface tension, the greater the spread. The surface tension of the ink is mainly adjusted by the ratio of various solvents in the formula (the surface tension of different solvents is different). Therefore, according to actual needs, it can be adjusted so that the ink droplets of the formula are printed to just cover the lower electrode area and at the same time not flow to the lower electrode area of adjacent sub-pixels. Depending on the formulation, the ratio of the diameters of the units formed by the ink droplets containing the quantum dot material before and after drying may be about 1.5:1 to about 1.1:1.

Adjusting the solid content of the ink can change the film thickness. Because in the embodiment of the present disclosure, there is no pixel isolation structure (no pixel defining part, such as isolation structure (bank)), so the thickness of the film layer cannot be changed by increasing or decreasing the number of printing ink droplets; The solid content of the formula itself is precisely controlled to meet the requirements of the spreading radius and film thickness.

In addition, the volatilization rate of the ink can also be adjusted to adjust the spread radius, and the overall volatilization rate can be controlled so that the solute in the ink droplet just spreads to the required radius when the solvent with relatively high volatility is just about to volatilize completely. If the desired radius is not reached, it is possible that the solute cannot move because it becomes more viscous in the remaining solvent, resulting in incomplete coverage of the lower electrode area. If the highly volatile solvent has not yet volatilized after reaching the radius, it may exceed the radius required for spreading, and will interfere with adjacent sub-pixels, which may cause color mixing. It should be understood, however, that these are not limiting and may instead be utilized in certain circumstances.

5A and 5B are schematic diagrams showing the relationship between the units of the printed light-emitting layer and the lower electrodes according to another embodiment of the present disclosure. In the embodiment shown in FIGS. 5A and 5B , the elongated pixels are taken as an example for illustration.

As shown in FIG. 5A , the unit 107 formed by printing ink droplets (multiple times) is strip-shaped with a width of L; the corresponding lower electrode is also strip-shaped with a width of l. Those skilled in the art will readily understand that a substantially elongated or any other shaped unit of the light-emitting layer can be formed by printing a plurality of ink droplets and drying them.

Assume that ideally, the centerline of the cell 107 formed by ink droplet printing is aligned with the centerline of the lower electrode. Then, similarly, in order to ensure coverage, the unit 107 is configured so that its half-width (half of the lateral dimension, L/2) is greater than or equal to the half-width (1/2) of the corresponding lower electrode 103 and the printing accuracy (a) And, that is, L/2≥l/2+a.

FIG. 5B shows the situation of

adjacent cells

1071 and 1072 and corresponding adjacent

lower electrodes

1031 and 1032 . Each

unit

1071 and 1072 is elongated and parallel in the direction in which it extends. The corresponding

lower electrodes

1031 and 1032 are each elongated and parallel in the direction in which they extend. Each

unit

1071 and 1072 and the corresponding

lower electrodes

1031 and 1032 satisfy the aforementioned configuration, that is, the half-width (L/2) of the unit is greater than or equal to the half-width (1/2) of the corresponding lower electrode and the printing accuracy ( a) sum.

Similarly, the center-to-center distance d between adjacent two

lower electrodes

1031 and 1032 is configured to be greater than or equal to the sum of the half-widths L1/2, L2/2 of the two

units

1071 and 1072 and the printing accuracy a1, a2. That is, d≧L1/2+L2/2+a1+a2. In the case of L1=L2=L, l1=l2=l, and a1=a2=a, the pitch d≧L+2a≧l+4a.

As an illustrative example, the initial conditions are set: 100ppi resolution, red, green and blue pixels are equal in width and distance, and the accuracy of the printing device is 10 microns. The side length of the corresponding square pixel is 254 microns (25400 microns/100), and the distance between the lower electrodes d=254/3=84.7 microns. The width of the cell formed by the ink is L≤d-2a=64.7 microns, and the width of the lower electrode is l≤L-2a=64.7-20=44.7 microns.

A method of manufacturing a light emitting device according to an embodiment of the present disclosure will be described below. 6A-6E show schematic diagrams of a method for fabricating a light emitting device according to an embodiment of the present disclosure.

As shown in FIG. 6A , a first substrate 101 having a plurality of first electrodes 103 thereon is provided. The first substrate 101 may be a TFT substrate (which may also be called a pixel substrate). Here, optionally, the first substrate may be cleaned. For example, the substrate is cleaned with a cleaning agent, rinsed with water, and then dried, and then subjected to surface plasma treatment for use.

Next, as shown in FIGS. 6B and 6C , a stack of functional layers including at least a light emitting layer including a plurality of units 107 is formed on the first substrate 101 . The plurality of units 107 are arranged corresponding to the corresponding first electrodes. There is no isolation structure between the plurality of cells 107 extending from the first substrate or the first electrode to the height of the plurality of cells or above to separate the plurality of cells. The isolation structure is also called pixel definition layer (PDL) in the prior art.

In some implementations, forming a stack of functional layers on the first substrate 101 may include the following steps: forming the layers of the light emitting layer corresponding to the plurality of first electrodes by an ink drop printing method. For the liquid printing units corresponding to the plurality of units, the ink droplets contain quantum dot materials; the liquid printing units are dried to form the plurality of units of the luminescent layer. In some implementations, the orthographic projection of each unit of the plurality of units on the first substrate covers the orthographic projection of the corresponding first electrode on the first substrate.

In some implementations, the preparation method of the light-emitting device does not include hydrophilic treatment or hydrophobic treatment on any layer of electrodes or functional layers.

In some implementations, optionally, as shown in FIG. 6B , a lower functional layer 105 is formed, and the lower functional layer covers at least the plurality of first electrodes 103; The plurality of units 107 of the light emitting layer are formed on the lower functional layer.

In some embodiments, the lower functional layer 105 may include a hole injection layer and a hole transport layer (not shown in the figure). In some implementations, the hole injection layer can be prepared as follows: formulate the hole injection material into an ink formulation suitable for coating, select appropriate coating parameters, and perform coating. After coating, the substrate is placed on a hot plate, to dry. Afterwards, the hole transport layer can be prepared as follows: the hole transport layer material is made into a printable formula, printed, and printed on the above hole injection layer material; then the substrate is transferred to a vacuum hot plate for drying. It should be understood that the method for preparing the lower functional layer described here is exemplary and not limiting; those skilled in the art will understand that various methods can be used to prepare the functional layer. In some implementations, the thickness of the hole injection layer (HIL) can be in the range of tens to hundreds of nanometers, such as 20nm-300nm, preferably 30nm-150nm; the thickness of the hole transport layer (HTL) can be in the range of tens to hundreds of nanometers. The range of several hundred nanometers, for example 10nm-200nm, preferably 15nm-100nm.

After preparing the optional lower functional layer, a light emitting layer may be formed on the lower functional layer. In some implementations, the quantum dot (QD) light-emitting layer can be prepared as follows: after the QD stock solution is centrifuged and precipitated, the formula that is redispersed into the printing solvent is made into a printable ink and loaded into the printing device; according to the set printing parameters , the QD ink is accurately printed on the mutually independent electrode areas of the pixel substrate, and the corresponding lower electrode area is completely covered; then the substrate is transferred to a vacuum hot plate for drying. In some implementations, the thickness of the QD light-emitting layer may range from tens to hundreds of nanometers, such as 10nm-100nm, preferably 15nm-60nm.

Afterwards, as shown in FIG. 6C , optionally, a similar or any suitable method may be used to form an upper functional layer 109 covering the plurality of units 107 of the light emitting layer. As an example, the above-mentioned functional layer may include an electron transport layer and/or an electron injection layer, each of which may have a thickness ranging from tens to hundreds of nanometers, such as 10nm-400nm, preferably 20nm-100nm.

Afterwards, as shown in FIG. 6D , a second electrode 301 is formed on the stack of functional layers. In some implementations, the second electrode 301 may be configured to be formed in one piece, covering the display area of one or more pixels (or sub-pixels). Optionally, as shown in FIG. 6E , a covering layer 303 capable of transmitting light is formed on the second electrode.

Fig. 7 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure. As shown in FIG. 7 , the light emitting device 700 further includes a spacer 701 . The spacer 701 is disposed on a side of the second electrode 301 away from the first electrode. The spacer 701 can be used to reduce the impact of pressure or stress on the pixels during packaging, so as to protect the pixels or light emitting units.

Here, as previously described, each of the plurality of units 107 of the light emitting layer, and corresponding portions of the corresponding first electrode 103 and the second electrode 301 may be included in a corresponding pixel. It should also be noted that the pixel referred to in this application may include sub-pixels unless stated otherwise.

In the case that the light emitting device 700 further includes an optional covering layer 303 , the spacer 701 is disposed on a side of the second electrode 301 away from the first electrode, and is opposite to the second electrode 301 through the covering layer 303 . The spacer 701 is arranged offset from the pixel, so as to avoid blocking the light emitted by the light-emitting unit, and can prevent pressure or stress from being transmitted to the light-emitting unit of the pixel.

Although in the embodiment shown in FIG. 7 , the spacer 701 is shown to be formed at the cover layer and shown to have an elliptical cross-sectional shape, this is merely exemplary and the present disclosure is not limited thereto. Spacers 701 may also be provided on a counter substrate (as shown at 801 in FIG. 8 ), which may also take any desired shape.

Here, as an example, the spacer 701 may be prepared by a printing method, for example, the spacer 701 may be formed by printing ink droplets at a desired position multiple times and drying. Alternatively, the spacer 701 can also be obtained by depositing a spacer material (eg, an organic or inorganic insulating material) and patterning it (eg, by etching using a mask).

As an example, the thickness of the spacer can be 0.5 micron-5 microns; the cross-sectional shape can be a positive trapezoid (formed by photolithography through a positive photoresist) or an inverted trapezoid (formed by photolithography through a negative photoresist); the material can be One or more of the following: polymethyl methacrylate (PMMA), polystyrene (PS), polyethylene terephthalate (PET), polycarbonate (PC), polyimide Amine (PI), Polyurethane (PU) and Polyvinyl Chloride (PVC).

The density and arrangement of the spacers are related to the pixel design and arrangement, which may be lower than the pixel resolution PPI.

Fig. 8 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure. As shown in FIG. 8 , compared with the light emitting device shown in FIG. 7 , the light emitting device 800 further includes an opposite second substrate 801 . The second substrate 801 and the first substrate 101 may be opposed and packaged. A light emitting unit (stack of the functional layers) is disposed between the first substrate and the second substrate. A filling material 803 may be filled between the second substrate 801 and the first substrate 101 .

Fig. 9 shows a schematic diagram of a light emitting device according to another embodiment of the present disclosure. As shown in FIG. 9 , the light emitting device 900 may include a first substrate 901 and an opposite second substrate 905 . A plurality of pixels 903 may be formed on the first substrate 901 . The pixel 903 or at least its light emitting unit may be a pixel or a light emitting unit prepared according to the foregoing embodiments of the present disclosure. A plurality of spacers 907 are formed on the second substrate 905 . The first substrate 901 and the second substrate 905 are encapsulated by an encapsulation compound 911 , and a filler 909 may be filled between the first substrate 901 and the second substrate 905 . Although the spacer 907 is shown here as having a trapezoidal cross-section, this is exemplary only and the present disclosure is not limited thereto, but may take any suitable shape.

One example of a method of manufacturing a display device according to the present disclosure is explained below.

First, a first substrate is provided. The first substrate may be a pixel substrate for forming pixels, and sometimes it may also be called a TFT substrate. Here, the first substrate may be a substrate without an isolation structure according to any of the foregoing embodiments or implementation manners.

Optionally, the first substrate may be cleaned, for example, solvent cleaning is performed on the first substrate with a cleaning agent, washed with water, and then spin-dried. Next, surface plasma treatment may be performed on the first substrate for use.

Then, a hole injection layer is formed on the first substrate. For example, the hole injection material can be formulated into a solution suitable for coating, and the coating can be performed by selecting appropriate coating parameters. After coating, the substrate was placed on a hot plate to allow the coated solution to dry. Thus, a hole injection layer was formed.

After that, a hole transport layer was formed. For example, the material of the hole transport layer can be made into a printable ink formulation, the first substrate on which the hole injection layer is formed is clamped in place, and printed by a printing device (for example, a nanomaterial printing device DMP2831) , so that the material is printed on the hole injection layer. The first substrate may then be dried through a vacuum hot plate. Thus, a hole transport layer was formed.

After that, a quantum dot (QD) layer is formed. For example, the QD stock solution can be redispersed into the printing solvent formula after centrifugal precipitation to make printable ink and load it into the printing device. According to the set printing parameters, the ink containing QD materials is accurately printed on the mutually independent electrode areas of the pixel substrate, and the electrode areas are completely covered. After printing, the substrate can be transferred to a vacuum hot plate for vacuum drying. In this way, a quantum dot layer is formed.

Fig. 10A shows a micrograph of the QD layer printed on the first substrate (here, the pixel substrate) in the light-emitting device prepared according to this example, and Fig. 10B is the corresponding scavenger scan result of the area shown in Fig. 10A. As shown in FIG. 10B , the formed QD film layer is substantially uniform from the edge to the middle film layer.

According to one aspect of the present disclosure, there is also provided an electronic device, which may include the light emitting device according to any embodiment or implementation manner of the present disclosure.

Those skilled in the art should appreciate that the boundaries between operations (or steps) described in the above embodiments are only for illustration. Multiple operations may be combined into a single operation, a single operation may be distributed among additional operations, and operations may be performed with at least partial overlap in time. Also, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be altered in other various embodiments. However, other modifications, changes and substitutions are also possible. Accordingly, the specification and drawings are to be regarded as illustrative rather than restrictive.

Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only, rather than limiting the scope of the present disclosure. The various embodiments disclosed herein can be combined arbitrarily without departing from the spirit and scope of the present disclosure. Those skilled in the art will also understand that various modifications may be made to the embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

A light emitting device, characterized in that it comprises:

first substrate;

a plurality of first electrodes located on the first substrate; and

A stack of functional layers located on the plurality of first electrodes, the stack includes at least a light-emitting layer, the light-emitting layer includes a plurality of mutually independent units, and the plurality of units correspond to the corresponding first electrodes to set,

Wherein, there is no isolation structure extending from the first substrate or the first electrode to the height of the plurality of units or above to separate the plurality of units between the plurality of units.
The light emitting device as claimed in claim 1, wherein the isolation structure is a pixel defining layer for defining pixels.
The light-emitting device according to claim 1, wherein the orthographic projection of each unit of the plurality of units on the first substrate covers the orthographic projection of the corresponding first electrode on the first substrate,

Wherein the plurality of units are set in one-to-one correspondence with the plurality of first electrodes.
The light emitting device according to claim 1, wherein the plurality of units are configured to be separated from each other, and

Wherein the laminate further includes an upper functional layer located on the light-emitting layer, at least a part of the upper functional layer is located between units of the plurality of units.
The light-emitting device according to claim 4, wherein between the units, the at least part of the upper functional layer and the lower functional layer under the light-emitting layer are not covered. contact with the part shaded by the emissive layer.
The light emitting device according to claim 1, wherein the laminate further comprises:

The lower functional layer under the light-emitting layer, wherein the surface properties of the portion of the lower functional layer overlapping with the unit of the light-emitting layer and the portion of the lower functional layer not overlapping with the unit of the light-emitting layer unanimous.
The light-emitting device according to claim 1, wherein the plurality of units of the light-emitting layer are formed by drying printed ink droplets, and the ink droplets contain quantum dot materials,

The plurality of units is configured, in top view:

For any unit, the lateral size of the unit is greater than or equal to the sum of the lateral size of the first electrode corresponding to the unit and twice the printing accuracy of the nozzle used for printing;

Between two adjacent units, the distance between the centers of the two first electrodes corresponding to the two adjacent units is greater than or equal to half of the respective transverse dimensions of the two adjacent units and is used for printing The sum of twice the printing accuracy of the nozzles.
The light-emitting device according to claim 1, wherein the laminate further comprises one or more functional layers under or above the light-emitting layer,

The one or more functional layers include at least one of the following: hole injection layer, hole transport layer, electron injection layer, electron transport layer, electron blocking layer, buffer layer.
The lighting device according to claim 1, characterized in that:

The light emitting device is a bottom emission type light emitting device, a top emission type light emitting device or a double side emission type light emitting device.
The light emitting device of claim 1, wherein each of the plurality of units of the light emitting layer and the corresponding first electrode are included in a corresponding pixel,

transistors are formed in the first substrate,

The light emitting device also includes:

an opposing second substrate; and

A spacer is arranged between the first substrate and the second substrate, and the spacer is arranged offset from the pixel.
A method for preparing a light-emitting device, comprising:

providing a first substrate having a plurality of first electrodes thereon; and

A stack of functional layers is formed on the first substrate, the stack includes at least a light-emitting layer, the light-emitting layer includes a plurality of units independent of each other, and the plurality of units are arranged corresponding to corresponding first electrodes,

Wherein, there is no isolation structure extending from the first substrate or the first electrode to the height of the plurality of units or above to separate the plurality of units between the plurality of units.
The method according to claim 11, wherein forming a stack of functional layers on the first substrate comprises:

By an ink drop printing method, forming liquid printing units corresponding to the plurality of units of the light-emitting layer corresponding to the plurality of first electrodes, the ink droplets containing quantum dot materials;

drying the liquid printing unit to form the plurality of units of the emissive layer;

Wherein the orthographic projection of each unit of the plurality of units on the first substrate covers the orthographic projection of the corresponding first electrode on the first substrate.
The method according to claim 12, wherein forming the stack of functional layers on the first substrate further comprises one or more of the following:

forming a lower functional layer, the lower functional layer covers at least the plurality of first electrodes, wherein the plurality of units of the light-emitting layer are located on the lower functional layer, and the lower functional layer is in contact with the The portion where the unit of the light emitting layer overlaps has the same surface properties as the portion of the lower functional layer that does not overlap with the unit of the light emitting layer; and

An upper functional layer covering the plurality of units of the light emitting layer is formed.
The method of claim 11, wherein an orthographic projection of each of the plurality of units on the first substrate covers an orthographic projection of a corresponding first electrode on the first substrate.
The method of claim 11, wherein said plurality of units are configured, in plan view:

For any unit, the lateral size of the unit is greater than or equal to the sum of the lateral size of the first electrode corresponding to the unit and twice the printing accuracy of the nozzle used for printing;

Between two adjacent units, the distance between the centers of the two first electrodes corresponding to the two adjacent units is greater than or equal to half of the respective transverse dimensions of the two adjacent units and is used for printing The sum of twice the printing accuracy of the nozzles.
The method of claim 13, wherein the plurality of units are configured to be separated from each other, and wherein at least a portion of the upper functional layer is located between units of the plurality of units.
The method according to claim 13, wherein the upper functional layer or the lower functional layer comprises at least one of the following: a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, Electron blocking layer, buffer layer.
The method of claim 11, further comprising:

forming a second electrode on the stack of functional layers,

Wherein each of the plurality of units of the light emitting layer, a corresponding first electrode and a corresponding portion of the second electrode are included in a corresponding pixel.
The method of claim 18, further comprising:

A spacer is provided, wherein the spacer is disposed on a side of the second electrode away from the first electrode and is disposed offset from the pixel.
An electronic device, characterized by comprising the light emitting device according to any one of claims 1-10.